I don’t know the whole context of this passage but I would guess D with the information given
Have several different views on that matter
a word governing, and usually preceding, a noun or pronoun and expressing a relation to another word or element in the clause, as in “the man on the platform,” “she arrived after dinner,” “what did you do it for ?”.
The best response to the counterargument is option D “Zoos may protect animals from being killed in the wild, but their lives are not much better if they're suffering.” since the focus of the counterargument is that in the zoo, animals are safer. The best response is to show that even if they are safer, animals' lives are not better if they are locked in a zoo and they are not happy there. Difference between living safer and living better, even if it implies facing the dangers in the wild.
The other options focus on the improvements the zoo has to make to give animals a better life in the zoo.
Hope exists even in the dark. Remove the points from this answer.
